We document a human-dolphin interaction involving the illegal feeding of wild Bottlenose Dolphins (Tursiops sp.) in Cockburn Sound, Western Australia from 1993-2003. In 1993 only one dolphin was considered conditioned to human interaction through food reinforcement. By 2001, 16% (n = 12) of the resident community of 74 adult dolphins were conditioned, and at least 14 dolphins were conditioned by 2003. Of the 13 conditioned dolphins of known sex, 11 (85%) were males. We observed conditioned dolphins initiating interactions by approaching recreational fishing boats and by residing for several hours at boat ramps and shore-based fishing sites. We only observed recreational fishers feeding dolphins, although anecdotal reports indicated additional feeding sources. We used belt transects to determine the densities of recreational boats and encounter rates for conditioned dolphins across habitats within Cockburn Sound. Encounter rates and boat densities were positively correlated, suggesting an association between recreational boat density and the ranging patterns of conditioned dolphins. This study demonstrates how illegal feeding interactions can intensify over time to affect a potentially biologically significant proportion of a local dolphin population. This emphasizes the need for early and pro-active intervention and demonstrates the value of longitudinal, individual-specific wildlife studies.
We examined the spatial distribution of water vole populations in four consecutive years and investigated whether the regional population processes of extinction, recolonisation and migration influence distribution and persistence. We examined how such regional processes are influenced by spatial variation in habitat quality. In addition, we assessed the relevance of metapopulation concepts for understanding the dynamics of species that deviate from classical metapopulation assumptions and developing conservation measures for them. Populations were patchy and discrete, and the patchy distribution was not static between years. Population turnover occurred even in the absence of predatory mink, which only influenced the network of populations at the end of the study. Most populations were clustered close together in the upper tributaries. Local population persistence was predominantly influenced by population size: large populations were more persistent. Recolonisation rates were influenced by isolation and habitat quality. The isolation estimates which best explained the distribution of water vole populations incorporated straight‐line distances, suggesting water voles disperse overland. The distribution of recolonised sites indicated that dispersing voles actively selected habitat on the basis of its quality. Water voles depart from some of the assumptions made by frequently used metapopulation models. In particular there is no clear binary distinction between suitable and non‐suitable habitat. Accounting for variation in habitat quality before investigating temporal changes in population distribution allowed us to demonstrate that the key metapopulation processes were important. The significance of regional population processes relative to local population processes may have increased in declining, fragmented populations compared to pristine regional populations. We hypothesise that although mink predation is likely to eventually cause regional extinction in many areas, metapopulation processes have delayed this decline. Consequently, conservation measures should take into account mink predation rates and regional population processes, before considering aspects of habitat quality.
One reason for the legislative restrictions on feeding dolphins in many parts of the world is the putative increased risk of injury to dolphins conditioned to human interaction through food reinforcement. However, there are few empirical data to support this. Here, we present data for a population of Bottlenose Dolphins Tursiops sp. in Cockburn Sound, in the city of Perth, Western Australia, indicating higher incidence of boat strike injury and fishing line entanglement for dolphins conditioned to taking food from humans, compared to others in the population that were not conditioned. The data support prohibitions on feeding dolphins and rigorous enforcement of existing regulations.
Although harmful human-wildlife interactions involving anthropogenic food sources are a significant issue for wildlife conservation, few studies have addressed whether social learning may influence how animals learn to use anthropogenic foods. We examined a long-term (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003) human-wildlife interaction involving the illegal feeding of bottlenose dolphins (Tursiops aduncus) by recreational fishers in south-western Australia. We developed predictor variables for whether dolphins learned to accept food handouts from human provisioners, based on biological (age-class, sex) and behavioural (ranging and association patterns) data for a population of 74 dolphins. Two variables provided clear predictors for whether dolphins became conditioned to food handouts: the use of areas with high densities of recreational boats (BOAT) and the average coefficient of association with previously conditioned dolphins (ASSOC). An individual was more likely to become conditioned when it spent more time in high boat density areas and when it spent more time with other conditioned dolphins. When considering all the models available, there was strong weight of evidence for the effects of ASSOC and BOAT on the response variable. We were unable to detect any effects of age-class and sex with the available statistical power. These findings suggest that social learning can facilitate the acquisition of undesirable and maladaptive behaviours in wildlife, and indicate the value of long-term individual-specific data for the conservation management of wildlife engaging in undesirable interactions with humans.
The ability of Tasmanian bettongs (Bettongia gaimardi) to locate hypogeous fungi (their main diet) was tested in a controlled laboratory situation. Bettongs dug directly over buried fungi significantly more often than they did over buried glass marbles or over disturbed soil. This ability was not enhanced as they gained experience. Bettongs dug more often over buried filter paper onto which fungus extract was absorbed than over control papers, and showed no discrimination between the outer and inner layers of the fungi. They preferred the odor of whole fungi to individual volatile compounds. They showed no reaction to the odor of the steroid ergosterol.
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